.98 



[SjENATK 



Y-\JV\ 



GONIATITES DISC0IDET7S. 



Pig. 3. A young individual, showing form of shell and direction of septa. 



Fig. 4. Diagram of septa. 



Fig. 5. A larger and nearly full-grown individual. 



Fig. 6. Diagram of septa, showing a greater sinuosity in the older specimens. 



GONIATITES UNIANGULARIS. 



G. uniangularis : Conrad, Jour. Acad. Nat. Sci. Phil'a, Vol. viil, pa. 268, pi. 16. fig. 4. 



6 (bis). 



This is a small species, showing an increased sinuosity in the 

 septa, a small dorsal lobe, with shallow dorsal saddle and a 

 defined dorso-lateral lobe. A larger specimen shows more sinuous 

 septa. 



The figure gives the form and proportions, with the direction 

 of the septa in the original of Mr. Conrad's description. 



Geological formation and locality. In the shales of the Ha- 

 milton group : at Moscow and Paterson's creek, Livingston co. 



GONIATITES UNIANQTJLAEIS. 



GONIATITES MITHRAX ( n.s.). 



This species is discoid and but moderately 

 gibbous in the middle of the volutions, and 

 regularly curving towards the back . There is 

 np perceptible umbilicus, the interior volutions 

 being entirely included. It has twice the dia- 

 meter of the figure, and the last chamber and 

 the aperture are unknown. Its similarity to 

 G. uniangularis, in the direction of the septa, 

 is remarkable ; but that species is proportion- 

 ally more expanded towards the ventral side 

 of the volutions, and a little flattened on the 

 sides towards the back. The outer volution in 

 that one is not so deepl}'^ occupied by the pre- 

 ceding ones, and the aperture is more elongated. 



Geological formation and localittj. In limestone of the age of the Upper Hcl- 

 derberg limestone, near Columbus (Ohio), received from Dr. Mann. The notice 

 and illustration of this spedcs are introduced here, for the purpose of comparison 

 with those of the Hamilton group. 



GONIATITES MITHRAX. 



